Coarse and fine adjustment device of the type using three concentric shafts

ABSTRACT

A coarse and fine adjustment device employs an assembly of three concentric shafts-a fine adjustment shaft, a drive shaft for moving an object supporting table, and a coarse adjustment shaft. A predetermined number of planetary balls are held by retaining surfaces provided by the respective shafts. The fine adjustment shaft is formed with an annular V-shaped groove. The balls are retained in the groove in engagement with the inclined surfaces thereof by inclined surfaces respectively provided on opposite sides of the balls by the drive and coarse adjustment shafts. The angle of engagement of the retaining surface provided by the drive shaft differs from the angle of engagement of the retaining surface of the coarse adjustment shaft.

United States Patent Kuroha COARSE AND FINE ADJUSTMENT DEVICE OF THETYPE USING THREE CONCENTRIC SHAFIS [72] Inventor: Noboru Kuroha, Tokyo,Japan [73] Assignee: Nippon Kogaku K.K., Tokyo, Japan [22] Filed: Aug.21, 1970 [21] Appl. No.: 65,792

[30] Foreign Application Priority Data Aug. 26, 1969 Japan ..44/67077[52] 0.8. CI. ..74/l0.52, 74/89. 17, 74/796,

350/86 [5]] Int. Cl ..F-l6h 35/18 [58] Field of Search ..'350/86;74/l0.52, 89, 89.17

[56] References Cited UNITED STATES PATENTS 2,877,651 3/1959 Erbe et al...350/86 M 1 Aug. 15, 1972 Primary Examiner-David Schonberg AssistantExaminer-Robert L. Sherman Attorney-Harry G. Shapiro 57] ABSTRACT Acoarse and fine adjustment device employs an assembly of threeconcentric shafts-a fine adjustment shaft, a drive shaft for moving anobject supporting table, and a coarse adjustment shaft. A predeterminednumber of planetary balls are held by retaining surfaces provided by therespective shafts. The fine adjustment shafi is formed with an annularV-shaped groove. The balls are retained in the groove in engagement withthe inclined surfaces thereof by inclined surfaces respectively providedon opposite sides of the balls by the drive and coarse adjustmentshafts. The angle of engagement of the retaining surface provided by thedrive shaft differs from the angle of engagement of the retainingsurface of the coarse adjustment shaft.

6 Claim, 4 Drawing Figures Patented Aug. 15, 1972 Nosoku HKUROHA HtjfLAT TOR NE Y COARSE AND FINE ADJUSTMENT DEVICE OF THE TYPE USING THREECONCENTRIC SHAFTS BACKGROUND OF THE INVENTION 1. Field of the InventionThis invention generally relates to an adjustment device, and moreparticularly to a coarse and fine adjustment device of the type whichuses three concentric shafts.

SUMMARY OF THE INVENTION It is the main object of the present inventionto overcome the above-mentioned limitations of the prior art devices andto provide a device which can accomplish accurate coarse and fineadjustments with a simple mechanism with ease.

Through the device of the present invention employs steel balls, it isentirely different in basic principle from known types of adjustmentdevices. The coarse and fine adjustment device of the inventioncomprises a fine adjustment shaft, a drive shaft for moving an objectsupporting table, a coarse adjustment shaft to which is imparted apredetermined degree of friction, and a predetermined number ofplanetary balls. The three shafts are concentrically arranged with oneanother and have respective retaining surfaceswhich engage and retainthe planetary balls. The angle of engagement or contact between theplanetary balls and the drive shaft and the angle of engagement orcontact B between the planetary balls and the coarse adjustment shaftare designed to satisfy the relation that 3 or a 5. V

The above and other objects and features of the present invention willbecome fully apparent when the following description is read inconnection with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a horizontal cross-sectionalview of the coarse and fine adjustment device according to an embodimentof the present invention.

FIG. 2 is a sectional view taken along line II-II of FIG. 1.

FIG. 3 is a diagrammatic view illustrating the principle of the presentinvention. I

FIG. 4 is a perspective view schematically showing an example ofapplication of the device of the present invention.

DESCRIPTION OF THE PREFERRED EMBODIMENT The invention will now bedescribed with respect to an example thereof as applied to the focusingdevice for a microscope.

Referring to FIG. 1, 2 and 4, a fine adjustment shaft 1 has knobs 2 and2 fixedly mounted at the opposite ends thereof, as by screws. An annularV-shaped groove 1a is formed circumferentially of the fine adjustmentshaft 1 at one end portion thereof adjacent to the knob 2. Adn've shaft3 extends concentrically and externally of the fine adjustment shaft 1and has a pinion 3a formed centrally thereof for engagement with a rack12a formed-in an object supporting table 12 to be described. A retainerportion 3b for engagement with planetary balls 11 is'formed on the driveshaft 3 at one end thereof which is adjacent to the V-shaped groove 1aand a knob member 3:; formed with a predetermined number of divisions orindicia on the end face thereof is integrally provided on the driveshaft 3 at the other end thereof.

A coarse adjustment shaft 4 extends in concentric relationship with thedrive shaft 3 and has a coarse adjustment knob 4a formed at one endthereof which is adjacent to the retainer portion 3b of the drive shaft3. A retainer plate 5' engaging the planetary balls 11 is secured to thecoarse adjustment knob 4a, by means of a screw 6. As shown, the fineadjustment shaft 1, drive shaft 3 and coarse adjustment shaft 4 arerotatably mounted tothe body portion 7 of the device and connectedtogetherfor relative rotation with respect to one another. The driveshaft 3 may be driven for light rotation by means of ball bearing 8. Thecoarse adjustment shaft 4 is arranged so that a predetermined-degree offriction may be imparted thereto from an adjustment ring 9 through afriction member 10, the ring 9 being screwed to the device body portion7. As best seen in FIGS. 1 and 2, the planetary balls 11 whose number ispredetermined are disposed on the annular V-shaped groove 1acircumferentially thereof in such a manner that these balls are retainedby the retainer portion 3b and retainer plate 5. As shown in FIG. 3,each of the balls is in engagement with the inclined surfaces of thegroove. The drive shaft retainer 3b on one side of the V-shaped grooveprovides a third inclined surface in engagement with each of the balls.The coarse adjustment shaft retainer means or plate 5 on the oppositeside of the groove provides a fourth inclined surface in engagement witheach of the balls. A spring washer 5a is provided to prevent the slip ofthe planetary balls 1 1.

It is seen in FIG. 3 that the planetary balls 11, retainer portion 3band retainer plate 5 are arranged so that the angle of contacta betweeneach ball 11 and retainer portion 3b and the angle of contact [3 betweeneach ball 11 and retainer plate 5 satisfy the relation that fl. Theangle of rotation 6 of the fine adjustment shaft 1 and the amount offine adjustment h provided thereby are in the following relation:

dud, (cos a cos [3) h DX (d.+l+d3) (d/1+4.

where D represents the pitch radius of the pinion 3a formed on the driveshaft 3, d0 the radius of the planetary ball 1 1, d1 the distance fromthe center of the fine adjustment shaft 1 to the point of contactbetween the planetary ball 1 l and the fine adjustment shaft 1, d2 thedistance from the center of the planetary ball 11 to the point ofcontact between the planetary ball 11 and the fineadjustment shaft 1, d3dOcos B the distance from the center of the planetary ball 11 to thepoint of contact between the planetary ball 11 and the retainer plate 5,and d4= docosa the distance from the center of the planetary ball 11 tothe point of contact between the planetary ball 11 and the drive shaft3.

From the foregoing equation, it will be seen that when the fineadjustment shaft 1 is rotated an angleO, the object supporting table 12to be described is displaced an amount h. The object supporting table 12is mounted for vertical sliding movement on the device body portion 7 bymeans of ball bearings 13, and the table is formed with a rack 12aengaging the pinion 3a of the drive shaft 3.

To provide a fine adjustment of the object supporting to. rotate andrevolve. At this stage the coarse adjustment shaft 4 and retainer plate5 are prevented from rotating by a predetermined friction impartedthereto by the friction member so that the drive shaft 3 may be rotatedin the same direction as the fine adjustment shaft 1 by a differentialamount corresponding to the difference between the aforesaid anglesa andB. As a result, the object supporting table 12 is vertically moved by anamount equal to that differential amount through the engagement betweenthe pinion 3a and rack 12a. Moreover, the rate of fine adjustment of theobject supporting table 12 may be suitably selected by suitablyselecting the angles of contact and [3 within the range ofa B.

To attain a coarse adjustment of the object supporting table 12, thecoarse adjustment knob 4a is first rotated. Upon rotation of this knob4a, the retainer plate 5, planetary balls 11, drive shaft 3 and fineadjustment shaft 1 are a all rotated to vertically move the objectsupporting table 12 by an amount equal to the amount of rotation of thecoarse adjustment shaft 4 through the engagement between the rack 12aand pinion 3a. The coarse adjustment of the object supporting table 12may also be accomplished by rotating the knob 30 for the drive shaft 3.

The angles of contacta and B may alternatively be in the relation that a13. In this case, it will be appreciated that rotation of the fine andcoarse adjustment knobs 2 and 4a in the same direction causes the fineand coarse adjustments of the object supporting table 12 to take placein the opposite direction to that in the case Ofa B.

The device of the present invention eliminates mechanical slack andprovides coarse and fine adjustment with a high degree of accuracy. Themechanism is simple, economical to manufacture and highly practi- 4 calin use.

What is claimed is: g 1. A device for coarse and fine adjustment of amovable table comprising a rotatable fine adjustment shaft having anannular V-shaped groove, a plurality of planetary balls disposed in thegroove each in engagement with the inclined surfaces of the groove, arotatable drive shaft concentric with the fine adjustment shaft havingmeans for cooperation with means associated with the table to move thetable, the drive shaft having retainer means on one side of the V-shapedgroove providing a third inclined surface in engagement with each of theplanetary balls, and a rotatable coarse adjustment shaft concentric withthe drive shaft having Eifilififii. ng a iB'ir3E*i% irb u? a$rrYl mentwith each of the planetary balls, the angle of engagement of the fourthsurface with the balls being different than the angle of engagement ofthe third surface.

2. A device for coarse and fine adjustment of a table according to claim1 including adjustable friction means cooperable with the coarseadjustment shaft.

3. A device for coarse and fine adjustment of a table according to claim1 wherein the angle of engagement of the third surface with each of theplanetary balls is greater than the angle of engagement of the fourthsurface.

4. A device for coarse and fine adjustment of a table according to claim1 wherein at least one of the drive shaft retainer means and the coarseadjustment shaft retainer means is displaceable in the direction of theaxes of the shafts.

5. A device for coarse and fine adjustment of a table according to claim1 wherein the drive shaft is provided with a knob member at the endthereof opposite the end having the retainer means, the knob memberhaving indicia thereon.

6. A device for coarse and fine adjustment of a table according to claim2 wherein the angle of engagement of the third surface with each of theplanetary balls is greater than the angle of engagement of the fourthsurface; wherein at least one of the drive shaft retainer means and thecoarse adjustment shaft retainer means is displaceable in the directionof the axes of the shafts; and wherein the drive shaft is provided witha knob member at the end thereof opposite the end having the retainermeans, the knob member having indicia thereon.

1. A device for coarse and fine adjustment of a movable table comprising a rotatable fine adjustment shaft having an annular Vshaped groove, a plurality of planetary balls disposed in the groove each in engagement with the inclined surfaces of the groove, a rotatable drive shaft concentric with the fine adjustment shaft having means for cooperation with means associated with the table to move the table, the drive shaft having retainer means on one side of the V-shaped groove providing a third inclined surface in engagement with each of the planetary balls, and a rotatable coarse adjustment shaft concentric with the drive shaft having retainer means on the opposite side of the V-shaped groove providing a fourth inclined surface in engagement with each of the planetary balls, the angle of engagement of the fourth surface with the balls being different than the angle of engagement of the third surface.
 2. A device for coarse and fine adjustment of a table according to claim 1 including adjustable friction means cooperable with the coarse adjustment shaft.
 3. A device for coarse and fine adjustment of a table according to claim 1 wherein the angle of engagement of the third surface with each of the planetary balls is greater than the angle of engagement of the fourth surface.
 4. A device for coarse and fine adjustment of a table according to claim 1 wherein at least one of the drive shaft retainer means and the coarse adjustment shaft retainer means is displaceable in the direction of the axes of the shafts.
 5. A device for coarse and fine adjustment of a table according to claim 1 wherein the drive shaft is provided with a knob member at the end thereof opposite the end having the retainer means, the knob member having indicia thereon.
 6. A device for coarse and fine adjustment of a table according to claim 2 wherein the angle of engagement of the third surface with each of the planetary balls is greater than the angle of engagement of the fourth surface; wherein at least one of the drive shaft retainer means and the coarse adjustment shaft retainer means is displaceable in the direction of the axes of the shafts; and wherein the drive shaft is provided with a knob member at the end thereof opposite the end having the retainer means, the knob member having indicia thereon. 